Peter J. Weinberger

MSM : I see�so you came in with AWK. How did AWK come about? Weinberger : Well, as I remember, I came over to ask --while I was doing this data base work in development-- (up the hill someplace)�I came over to ask Aho about parsing because there [were these�there was this sort of current about extensible languages. And it seemed like it would be convenient to, you know, add�. It was one of those things where the name is more than what the technique actually provided, ok. Extensible languages seems very desirable. The user could adjust the syntax in the language in some way and the composite would somehow automatically understand it and it would all be more convenient for the user, and so forth. And, um�Al was not very enthusiastic about that approach for�the technical reasons were that he was at that time, and I think as everybody is now, much more in favor of table-driven parsers, in particular LR parsers, and if you�ve compiled a table it�s a little hard to adjust the syntax. And I suspect in retrospect he didn�t think much of the usefulness of the technique. And I think in retrospect he was probably right. Extensible languages is not something that worked out well. And the places where people are very enthusiastic about tailoring the syntax of�of�for users. There�s two of them that I can think of. One is emacs, which is this editor where you can bind keys in weird ways. And the other is with something called Read Macros in Lisp. And the effect of both of those is that I can�t enter your world, because each person personalizes his world in some�some way they like, and nobody else can cope. So in fact it�s not at all clear it was a good idea. Weinberger : I did�we discussed syntax a lot. Kernighan likes free-form syntax. That is without extra parentheses and stuff, because it�s so much easier to type. The problem with free-form syntax is that after a while the language becomes very ambiguous, and it�s hard to see what it all means. I like more parentheses and stuff like that. So we tried out a couple of different syntaxes. We spent a lot of time discussing, all of us discussing, this pattern-and-action business�was that really what we wanted to do? And several rather more elaborate ways of doing it which were more database-y, which in the end didn�t go in because either�we couldn�t either�it turned out they didn�t add anything. It was just do the same stuff anyway. Or we can figure out exactly what they meant and how to make them work. I think I wrote the first�a very early translator to try to�all it did was take these provisional languages and put out C-code so you compile it. And --this may not be quite right-- I think Kernighan wrote an interpreter, and then I wrote an interpreter and then some years later Kernighan re-wrote the interpreter. Or we both re-wrote the interpreter. Weinberger : I ought to say a few words about the appearance to the users of the whole thing. Yeah, the pattern action stuff is�I�m not sure that yacc�yacc must have been in our mind, because in those days especially there were not very many models of that stuff. There�s another, I forget whether these are Markov somethings or Post somethings�one of these constructs in theoretical computer science, right? Maybe they�re Post-productions�you match the left side and transform according to the right side, which is also vaguely the yacc model. It�s not just yacc, it�s several things. The C-like appearance of it all is�instead�. Well, the idea is if you made it just like C then you wouldn�t have to explain it to the people around here, right?. Or, that�s how I remember the idea. We may not have been quite so concrete about it. Weinberger : For an academic computer center, they had a first-class place. It was very innovative. They had their own operating system, which was not a bad operating system. Like all home grown operating systems, it had these places with just appalling weakness, but usually users don�t notice them�just like our home grown ope